1. Field of the Invention
The present invention relates to a texture mapping system and method, and more particularly, to a texture mapping system and method using a texture cache for minimum capacity and minimum access time.
2. Description of the Related Art
In general, in a three-dimensional (3D) graphics field, most of pixels on a screen are generated by texture mapping, so that performance of the graphics depends on performance of the texture mapping.
FIG. 1 shows an embodiment of a conventional graphic processor for texture mapping. The graphic processor includes a geometry processor 100, a rasterizer 110, a monitor 120 and a frame buffer memory/texture memory 130. The geometry processor 100 calculates changes of geometric information on an object to be rendered as a unit of a polygon, and converts the result to be projected on a screen of the monitor 120. The rasterizer 110 calculates a parameter necessary for rasterization from the projected polygons and generates pixel values in the polygons using the parameter. The frame buffer memory/texture memory 130 for storing intensity data of each pixel forming an image, allots its portion partially acts as a texture memory region for storing texel data to be texture-mapped. In a structure as shown in FIG. 1, a memory bandwidth is narrow, so that a fetch speed of the texel data is undesirably reduced.
To solve the problem, a texture memory for storing image data to be texture-mapped may be provided separately from the frame buffer memory. Accordingly, the memory bandwidth may increase, however, the data fetch speed for access to an external memory is still limited. Also, a memory capable of storing one texture, where one scene may be composed of dozens or hundreds of texture images, may be embedded in the rasterizer. Here, the memory fetch speed increases, however, a memory having capacity as large as the texture image data can be stored is required for the rasterizer.
As described above, in texture mapping, bottleneck problems may occur in fetching the texel, which is data for the texture mapping, from the texture memory. Preferably, the fetch speed of the texel is increased by rapidly fetching data using a texture cache. However, the texture image data is two-dimensional, and each of the objects to be texture-mapped is momentarily changed on the screen by shifting of the eye position. Therefore, the address value to pre-fetch the texel is not predictable.